Solid–Liquid Equilibria, Density, Viscosity, Metastable Zone Width, and Thermal Conductivity of a Binary System of Ethylene Glycol and 1,2-Butanediol from a Coal-to-Ethylene Glycol Process

The phase diagram of the ethylene glycol (EG)/1,2-butanediol (BDO) system at 227.05 to 260.25 K was determined and fitted by the modified Apelblat model with an average relative deviation (AARD) of 1.02%. The density and kinematic viscosity of EG/BDO were measured at temperatures of 238.15 to 263.15 K, where the mass fraction of EG was 90.02 to 100%. The experimental results were fitted and regressed by the least-squares method, and the AARD values were 0.04 and 3.04%, respectively. The density and kinematic viscosity had good correlation with the temperature and EG mass fraction. The metastable zone width of EG/BDO was measured. The results showed that the metastable zone width increased with a decrease in the EG content. The thermal conductivity of the EG coarse crystal layer from the EG/BDO mixture, with the mass fraction of EG from 90.25 to 100%, was measured at a temperature range of 250.57 to 258.53 K. The EG coarse crystal layer had a poor thermal conductivity, and its thermal conductivity dependence of temperatures was described by the least-squares method with AARDs smaller than 1.78%. The work provided a theoretical foundation for the melt crystallization separation of coal to EG.